Access to sketchpad properties from a Python script

Working on the problem of changing some features of a MCQ form (see my previous post), I realized that I would probably not be able to change a text-based design according to my needs. So I am trying to design a MCQ template in a sketchpad, using named objects and mouse-response.

In order to facilitate the selection of an object, I would like to highlight it when the mouse cursor goes over it, for instance by changing its color. So I need an additional Python script to do that. Is it possible to reference the sketchpad and/or some of its objects from the script or is it necessary to create an entire sketchap and do all the job with Python code ?

I have not seen any mention of this possibiity in the documentation, so I am not very optimistic about the result. But some workarounds may be possibe ?